Ngaphandle kolawulo lwe-impedance, ukubonakaliswa kokubonisa uphawu kunye nokugqwetha kuya kubangelwa, kukhokelela kukusilela koyilo. Imiqondiso eqhelekileyo, enje ngebhasi ye-PCI, ibhasi ye-PCI-E, i-USB, i-Ethernet, inkumbulo ye-DDR, uphawu lwe-LVDS, njl. Impedance control ultimately needs to be realized through PCB design, which also puts forward higher requirements for Ibhodi PCB technology. After communication with PCB factory and combined with the use of EDA software, the impedance of wiring is controlled according to the requirements of signal integrity.

Iindlela ezahlukeneyo zokubamba zingabalwa ukufumana ixabiso le-impedance ehambelanayo.

Imigca ye Microstrip

It consists of a strip of wire with the ground plane and dielectric in the middle. Ukuba i-dielectric engagungqiyo, ububanzi bomgca, kunye nomgama wayo ukusuka kumhlaba ojikelezayo uyalawuleka, impedance yempawu yayo iyalawuleka, kwaye ukuchaneka kuya kuba ngaphakathi kwe-5%.

How to control PCB wiring impedance

Umgca

Umgca weribhoni ngumtya wobhedu embindini we-dielectric phakathi kweenqwelomoya ezimbini zokuqhuba. Ukuba ubukhulu nobubanzi bomgca, i-dielectric eqhubekayo yaphakathi, kunye nomgama phakathi kweeplani zomhlaba zomhlaba ezimbini zilawulwa, impedance yempawu yomgca iyalawuleka, kwaye ukuchaneka kungaphakathi kwe-10%.

How to control PCB wiring impedance

Ubume bebhodi enemigangatho emininzi:

Ukulawula i-PCB ye-impedance kakuhle, kufuneka uqonde ubume be-PCB:

Ngokwesiqhelo le nto siyibiza ngokuba yibhodi ye-multilayer yenziwe ngeplate engundoqo kunye nephepha elomeleleyo eliqinileyo kunye nelinye. Ibhodi engumqobo lukhuni, ubukhulu obuthile, iipleyiti ezimbini zesonka sobhedu, ezizizinto ezisisiseko zebhodi eprintiweyo. Kwaye ke isiqwenga esinganyangekiyo senza oko kubizwa ngokuba kukungena ngaphakathi, kudlala indima yokubopha isiseko seplate, nangona kukho ubukhulu bokuqala, kodwa kwinkqubo yokucinezela ubukhulu bayo buza kubakho utshintsho.

Ngokwesiqhelo amacala ombane e-dielectric amabini angaphandle e-multilayer a manzi manzi, kwaye izingqimba zeefoyile zobhedu ezahlukileyo zisetyenziswa ngaphandle kwala maleko mabini njengefoyile yangaphandle yobhedu. Ukucaciswa koqobo lokulinganisa kwefoyile yobhedu yangaphandle kunye nefoyile yangaphakathi yobhedu ngokubanzi yi-0.5oz, 1OZ, 2OZ (1OZ imalunga ne-35um okanye i-1.4mil), kodwa emva kothotho lonyango lomphezulu, ukutyeba kokugqibela kwefoyile yobhedu engaphandle kuya kunyuka ngokubanzi malunga 1OZ. Ifoyile yobhedu yangaphakathi sisigqubuthelo sobhedu kumacala omabini epleyiti engundoqo. Ubunzima bokugqibela bohluka kancinane kubungakanani bokuqala, kodwa ubukhulu becala buncitshiswa ngum ngenxa yeetching.

Ubume obungaphandle bebhodi ye-multilayer bubungqingqwa bokumelana ne-welding, yile nto sihlala sisithi “ioyile eluhlaza”, kunjalo, inokuba tyheli okanye eminye imibala. Ubungakanani be-solder ukumelana nocingo ngokubanzi akukho lula ukufumanisa ngokuchanekileyo. Indawo engenafoyile yobhedu kumphezulu ityebile kancinci kunendawo enefoyile yobhedu, kodwa ngenxa yokunqongophala kobunzima befoyile yobhedu, ke ifoyile yobhedu isabonakala ngakumbi, xa sichukumisa umphezulu webhodi eprintiweyo ngeminwe yethu.

Xa ubungakanani bebhodi eprintiweyo benziwe, kwelinye icala, ukhetho olufanelekileyo lweeparitha zezinto ezifunekayo, kwelinye icala, ubukhulu bokugqibela bephepha eliphilisiweyo liya kuba lincinci kunobunzima bokuqala. Oku kulandelayo sisakhiwo esi-laminated se-6-layer:

How to control PCB wiring impedance

Iparameters PCB:

Izityalo ezahlukeneyo zePBB zinomahluko omncinci kwiiparameter zePCB. Ngokunxibelelana nebhodi yesekethe yenkxaso yezobuchwephesha, sifumene idatha yeparameter yesityalo:

Umphezulu ngefoyile ye yobhedu:

Zintathu izinto ezenziwe ngefoyile yobhedu enokusetyenziswa: 12um, 18um kunye 35um. Ubunzima bokugqibela emva kokugqiba malunga ne-44um, 50um kunye ne-67um.

Ipleyiti engundoqo: I-S1141A, i-standard standard ye-FR-4, iipleyiti ezimbini zesonka ezinezonka zihlala zisetyenziswa. Ukucaciswa kokukhetha kunokuchongwa ngokunxibelelana nomenzi.

Ithebhulethi ephilisiweyo:

Ukucaciswa (ubukhulu bokuqala) ngama-7628 (0.185mm), 2116 (0.105mm), 1080 (0.075mm), 3313 (0.095mm). Ubunzima bokwenyani emva kokucinezela kuhlala malunga ne-10-15um ngaphantsi kwexabiso lokuqala. Amacwecwe amathathu anyangiweyo ubuninzi anokusetyenziselwa umaleko ofanayo wokungena, kwaye ubukhulu beepilisi ezintathu eziphilisiweyo azinakufana, ubuncinci iipilisi ezinokusetyenziswa ezinesiqingatha zinokusetyenziswa, kodwa abanye abavelisi kufuneka basebenzise ubuncinci ezimbini . Ukuba ukutyeba kwesiqwenga esinganyangekiyo akwanelanga, ifoyile yobhedu kumacala omabini epleyiti esisiseko inokuxhonywa, emva koko isiqwenga esiphilisiweyo singadityaniswa macala omabini, ukuze umaleko wokungena ngaphakathi kufezekisiwe.

Umaleko welding umaleko:

Ubungakanani be-solder yokumelana nocwecwe kwi-foil foil yi-C2≈-8-10um. Ubungakanani be-solder yokumelana nocwecwe kumphezulu ngaphandle kwefoyile yobhedu yi-C1, eyahluka ngokobunzima bobhedu ngaphezulu. Xa ubukhulu bobhedu phezu komhlaba bungu-45um, C1≈13-15um, kwaye xa ubukhulu bobhedu phezu komhlaba bungu-70um, C1-17-18um.

Icandelo lokuhamba:

Singacinga ukuba icandelo lomnqamlezo wocingo luxande, kodwa eneneni yitrapezoid. Ukuthatha umaleko we-TOP njengomzekelo, xa ubukhulu befoyile yobhedu yi-1OZ, umphetho ongezantsi we-trapezoid yi-1MIL mfutshane kunomphetho ongezantsi. Umzekelo, ukuba ububanzi bomgca bungu-5MIL, ke amacala aphezulu nasezantsi amalunga ne-4MIL kwaye amacala asezantsi nangaphantsi amalunga ne-5MIL. Umahluko phakathi kwemiphetho ephezulu neyasezantsi inxulumene nobhedu. Itheyibhile elandelayo ibonisa ubudlelwane phakathi kwephezulu kunye nezantsi kwetrapezoid phantsi kweemeko ezahlukeneyo.

How to control PCB wiring impedance

Ukuvunyelwa: Ukuvunyelwa kwamashiti anyangekiweyo ahambelana nobukhulu. Le tafile ilandelayo ibonisa ubukhulu kunye neeparamitha zokuvumeleka zeentlobo ezahlukeneyo zamashiti anyangiweyo:

How to control PCB wiring impedance

Ukuhlala kwe-dielectric yeplate inxulumene nezinto ezisetyenzisiweyo. Ukuqhubeka kwe-dielectric yeplate ye-FR4 yi-4.2 – 4.7, kwaye iyancipha ngokwanda kwamaxesha.

Ilahleko le-dielectric factor: izixhobo zedelectric eziphantsi kwentshukumo yokutshintsha kwendawo yombane, ngenxa yobushushu kunye nokusetyenziswa kwamandla kuthiwa kukulahleka kwe-dielectric, kuhlala kuchazwa yilahleko ye-dielectric factor Tan δ. Ixabiso eliqhelekileyo le-S1141A ngu-0.015.

Ubuncinci bomgca wobubanzi kunye nokushiyana komgca wokuqinisekisa ukuqinisekisa ngomatshini: 4mil / 4mil.

Isixhobo sokubala sokulinganisa sokungenisa:

Xa siqonda ubume bebhodi ye-multilayer kunye nokuqonda iiparameter ezifunekayo, sinokubala i-impedance ngokusebenzisa isoftware ye-EDA. Ungasebenzisa iAllegro ukwenza oku, kodwa ndincoma iPolar SI9000, sisixhobo esihle sokubala impedance yempawu kwaye ngoku isetyenziswa yimizi mveliso emininzi yePCB.

Xa ubala ukungahambelani kweempawu zangaphakathi kwempawu zombini kunye nomgca wesiphelo esinye, uya kufumana kuphela umahluko omncinci phakathi kwePolar SI9000 kunye neAllegro ngenxa yeenkcukacha ezithile, ezinje ngemilo yecandelo lomnqamlezo wocingo. Nangona kunjalo, ukuba kubalwa impedance yesimpawu somqondiso ongaphezulu, ndicebisa ukuba ukhethe umfuziselo odityanisiweyo endaweni yemodeli yomphezulu, kuba iimodeli ezinjalo zithathela ingqalelo ubukho bokumelana ne-solder, ke iziphumo ziya kuchaneka ngakumbi. Oku kulandelayo sisikrini esisecaleni somda womhlaba owahlulwe ngokungafaniyo obalwe ngePolar SI9000 ithathela ingqalelo umaleko wokumelana nesoder:

How to control PCB wiring impedance

Kuba ubukhulu be-solder yokumelana nolawulo abulawulwa ngokulula, indlela enokusetyenziswa nayo inokusetyenziswa, njengoko kucetyisiwe ngumvelisi webhodi: thabatha ixabiso elithile kwimodeli yokubala yeSurface. Kuyacetyiswa ukuba ukungangqinelani kwe-impedance ibe ngu-8 ohms kunye nesiphelo esisiphelo esinye sibe ngu-2 ohms.

Umahluko weemfuno zePCB zewiring

(1) Chonga imowudi ye-wiring, iiparameter kunye nokubala kwe-impedance. Zimbini iintlobo zomahluko weendlela zendlela yomgaqo: umaleko wangaphandle imo yokwahlula imo yendlela kunye nolwahlulo lwangaphakathi lwendlela yokwahlula imo. Ukuthintela kungabalwa ngesoftware yokubala ye-impedance (efana ne-POLAR-SI9000) okanye ifomula yokubala ye-impedance ngokuseta okufanelekileyo kweparameter.

(2) Imigca ye-isometric efanayo. Chonga ububanzi bomgca kunye nokushiya izithuba, kwaye ulandele ngokungqongqo ububanzi bomgca obaliweyo kunye nezithuba xa uhamba. Isithuba phakathi kwemigca emibini kufuneka sihlale singatshintshanga, Oko kukuthi, ukugcina ukufana. Zimbini iindlela zokuthelekisana: enye kukuba le mizila mibini ihamba kwicala elinye icala-nge-icala, kwaye enye kukuba le mizila mibini ihamba ngaphezulu komaleko ongaphantsi. Ngokubanzi zama ukunqanda ukusebenzisa umqondiso umahluko phakathi kweengqimba, oko kukuthi kuba kulungiso lwangempela lwe-PCB kwinkqubo, ngenxa yokuchaneka kokulungelelaniswa kokulungelelaniswa okuthe tye kuncinci kakhulu kunokuba kubonelelwe phakathi kokuchaneka kokuchaphazeleka, nakwinkqubo yokulahleka kwelemitha elaminethiweyo, awunakuqinisekisa ukuba umahluko phakathi komgca olinganayo ulingana nobukhulu be-dielectric ye-interlayer, iya kubangela umahluko phakathi kwamanqanaba okwahluka kotshintsho lwe-impedance. Kuyacetyiswa ukuba usebenzise umahluko ngaphakathi koluhlu olufanayo kangangoko.